When a voltage is applied to a signal pin of an IC (Integrated Circuit) when a power source of the IC is in a cut off state, a large amount of current may flow into the IC. Therefore, the IC may be damaged or degraded in reliability. A structure for avoiding this problem is called a “Hot Swap” (hot swap) design or may be referred to as a “hot swappable” component.
A withstanding voltage of a device element, such as a MOSFET, mounted in an LSI (Large-Scale Integration) product of a state-of-the-art design process (e.g., the smallest semiconductor features) will often be lowered to 1.8 V, for example, to enable a higher speed operation and lower power consumption. However, there are mounted components for some LSI products that still are using older generation design processes that might be mounted on the same board with components using the state-of-the-art design processes. In interfacing between the different generation LSI products, data is generally exchanged at a standard signal level (for example, 3.3 V) used by the older generation LSI components. From such a circumstance, the LSI product using the state-of-the-art process employs a circuit design that requires the element to be able handle a signal at a voltage level equal to or greater than the withstanding voltage level of the element. Such a circuit design is called a “tolerant design.”
When a tolerant design is implemented, the overall operation of the circuit typically becomes slower in general. In addition, there is no proposed integrated circuit design in which a tolerant design is implemented in a hot swap design of an IC.